Farm-to-food study aims to understand the effect of manure management practices on antibiotic resistance and residues

Pilot-scale anaerobic digestion reactors at the USDA Beltsville Agricultural Research Center. The replicate digesters, designed by University of Maryland researcher Stephanie Lansing, will be used in the new study. Credit: Edwin Remsberg/University of Maryland

University researchers partner with dairy farms across the Northeast on innovative study

“Our findings could have important implications for human health and food safety.”

Diana Aga, Henry M. Woodburn Professor of Chemistry

University at Buffalo

Download High-Res Images:

Pilot-scale anaerobic digestion reactors at the USDA Beltsville
Agricultural Research Center (top), and the interior of one of the
digesters (bottom). The replicate digesters, designed by University
of Maryland researcher Stephanie Lansing, will be used in a new
study that partners dairy farms with university researchers to
examine the effect of manure management techniques on preventing
the occurrence and spread of antimicrobial-resistant bacteria,
resistance genes and antibiotic residues. Credit: Edwin
Remsberg/University of Maryland

BUFFALO, N.Y. — Researchers from four U.S.
universities are teaming up with dairy farms across the Northeast
and Mid-Atlantic to study the effect of three different manure
management techniques on preventing the occurrence and spread of
antimicrobial-resistant bacteria, genes tied to resistance, and
antibiotic residues — traces of antibiotics and the compounds
they break down into.

Investigations on the occurrence and spread of antibiotic
resistance have been mostly conducted in the clinical settings.
However, there are concerns that discharges from municipal
wastewater and agricultural wastes may also contribute to the
occurrence and spread of antibiotic resistance in the environment.
Therefore, it is important to study how manure management practices
and manure treatment systems can reduce the risk of antibiotic
residues entering local waterways.

Although there has not been direct evidence of resistance
spreading as the result of antimicrobial and antibiotic use on
dairy farms, given the potential risk, a team of scientists —
led by the University at Buffalo, in partnership with Cornell
University, the University of Maryland and the University of
Michigan — will investigate the fate of therapeutic
antimicrobials used in dairy herds by examining if and how various
methods to treat manure affect the viability of residuals
monitored, and the potential movement of any residuals from farms
to the environment.

“Our findings could have important implications for human
health and food safety,” said lead researcher Diana Aga,
Henry M. Woodburn Professor of Chemistry in the UB College of Arts
and Sciences. “Animal manure is recycled to a farm’s
land base for use as organic fertilizer for growing crops to feed
cows. This means that there is the potential for antibiotics and
antibiotic-resistant bacteria to escape from the manure into the
environment, potentially entering waterways or being taken up by
plant material used as cow feed.”

The $1 million project, funded by the USDA’s National
Institute of Food and Agriculture, will evaluate how well three
different waste-processing techniques — anaerobic digestion,
composting, and long-term storage — remove drugs and germs in
excrement. To evaluate the techniques, the scientists will collect
manure samples from six dairy farms in New York State, three in
Maryland and two in Pennsylvania. Samples will be gathered before
and after treatment, and tested for levels of antibiotics,
antibiotic-resistant bacteria and resistance genes.

Additional techniques will be used to explore anaerobic
digestion, an advanced treatment method that employs microorganisms
to break down and convert biodegradable matter into products that
include biogas, liquid fertilizer and solid matter that is
sometimes repurposed as bedding for animals.

Besides examining manure that has undergone this process on
farms, the team will spike manure with antibiotics and resistance
genes in controlled experiments that use anaerobic bioreactors in
the lab at the University of Michigan, as well as larger scale
anaerobic digestion reactors designed and built by Stephanie
Lansing, a scientist on the project and an associate professor of
environmental science and technology at the University of
Maryland.

And while dairy farm manure is only rarely used to fertilize
crops for human consumption, the team will also grow three food
crops to see whether the plants take up antibiotics and resistance
genes from treated and untreated manure — potatoes (grown
below ground), lettuce (grown above ground and eaten fresh), and
corn (grown above ground and eaten cooked).

“Dairy farming is the highest valued agricultural business
in New York State,” said research team member Curt Gooch, a
Senior Extension Associate in Cornell University’s College of
Agriculture and Life Sciences. “Dairy farmers have used cow
manure to organically fertilize feed crops since cows have been
housed in barns. Looking specifically at the effect of manure
handling systems on manure residuals provide the industry an
opportunity to better understand current manure handling practices
and their effect on certain constituents not studied much
before.”

Additionally, the team includes extension/outreach specialists
at Cornell and the University of Maryland who will monitor
antibiotic use at participating farms, understand the farms’
waste-processing methods, and raise awareness of advanced manure
management technologies.

Senior scientists on the project include Aga at UB; Lauren
Sassoubre in the Department of Civil, Structural and Environmental
Engineering in UB's School of Engineering and Applied Sciences;
Lansing and Gary K. Felton of the University of Maryland; Gooch of
Cornell University; and Krista Wiggington and Lutgarde Raskin of
the University of Michigan.